Stable controller design for linear systems

This paper is concerned with the problem of suboptimal stable mixed H2/H∞ control for linear time-invariant systems. The designed controllers are required to satisfy a prescribed H∞ performance bound or a prescribed degree of stability. By reducing the stable controller synthesis problem to a multiobjective state feedback control problem for two different state models, sufficient conditions for the solvability of the considered problem are given in terms of solutions to algebraic Riccati equations and matrix inequalities. LMI-based iterative algorithms are developed to solve the stable controller synthesis problem. All of the proposed algorithms are shown to be convergent. An example is given to illustrate the proposed methods.published_or_final_versio

Self-Perceived Pain Assessment Knowledge and Confidence (Self-PAC) Scale for Cancer and Palliative Care Nurses: A Preliminary Validation Study

© 2018 American Society for Pain Management Nursing Background: Pain is highly prevalent in all health care settings, and frequently poorly managed. Effective pain management is predicated on a continuous cycle of screening, assessing, intervening and evaluating. Identifying gaps in nurses’ self-perceived pain assessment competencies is an essential first step in the design of tailored interventions to embed effective pain assessment into routine clinical practice, and improve patient reported pain outcomes. Yet, few validated instruments focus on the competencies required for undertaking a comprehensive pain assessment, with most focusing on clinician's pain management competencies. Aim: To examine the validity of the ‘Self-Perceived Pain Assessment Knowledge and Confidence’ (Self-PAC) Scale. Design: Preliminary instrument validation. Setting: Two Australian cancer and palliative care services. Participants/Subjects: 186 cancer and palliative care nurses. Methods: The Self-PAC Scale was administered to participants online. Factor Analyses, including Exploratory and Confirmatory, were applied to examine the structural validity, Cronbach's alpha was calculated for internal consistency. Criterion validity was investigated by comparing responses from experienced and non-experienced nurses. Results: Two components resulted with a single factor structure for pain assessment confidence and a two-factor structure for the knowledge of pain assessment. The factor loading for the subscales ranged from 0.653 to 0.969, with large proportions of the variances explained by the factors. Cronbach's alpha of the subscales ranged from 0.87-0.92 and significant difference in responses were found between experienced and non-experienced nurses. Conclusion: Preliminary validation of the Self-PAC Scale suggests that it is a helpful instrument for assessing cancer and palliative care nurse’ pain assessment competencies

A Mixed-Methods, Randomized, Controlled Feasibility Trial to Inform the Design of a Phase III Trial to Test the Effect of the Handheld Fan on Physical Activity and Carer Anxiety in Patients with Refractory Breathlessness

© 2016 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved. Context The handheld fan is an inexpensive and safe way to provide facial airflow, which may reduce the sensation of chronic refractory breathlessness, a frequently encountered symptom. Objectives To test the feasibility of developing an adequately powered, multicenter, multinational randomized controlled trial comparing the efficacy of a handheld fan and exercise advice with advice alone in increasing activity in people with chronic refractory breathlessness from a variety of medical conditions, measuring recruitment rates; data quality; and potential primary outcome measures. Methods This was a Phase II, multisite, international, parallel, nonblinded, mixed-methods randomized controlled trial. Participants were centrally randomized to fan or control. All received breathlessness self-management/exercise advice and were followed up weekly for four weeks. Participants/carers were invited to participate in a semistructured interview at the study's conclusion. Results Ninety-seven people were screened, 49 randomized (mean age 68 years; 49% men), and 43 completed the study. Site recruitment varied from 0.25 to 3.3/month and screening:randomization from 1.1:1 to 8.5:1. There were few missing data except for the Chronic Obstructive Pulmonary Disease Self-Efficacy Scale (two-thirds of data missing). No harms were observed. Three interview themes included 1) a fan is a helpful self-management strategy, 2) a fan aids recovery, and 3) a symptom control trial was welcome. Conclusion A definitive, multisite trial to study the use of the handheld fan as part of self-management of chronic refractory breathlessness is feasible. Participants found the fan useful. However, the value of information for changing practice or policy is unlikely to justify the expense of such a trial, given perceived benefits, the minimal costs, and an absence of harms demonstrated in this study

Identifying factors that predict worse constipation symptoms in palliative care patients: A secondary analysis

© Copyright 2017, Mary Ann Liebert, Inc. 2017. Objective: The aim of this work was to investigate whether variables identified as likely to impact the experience of constipation in other clinical settings similarly affected the experiences of constipated palliative care patients. Background: The majority of palliative care patients with cancer are likely to be bothered by constipation symptoms at some point in their disease trajectory. Despite this, it remains unclear as to which factors predict more severe problems. Methods: This study was conducted in a sample of 94 constipated palliative care patients who were asked to voluntarily complete a series of questions regarding their demographic and other characteristics, including whether they had chronic constipation symptoms, that is, constipation symptoms for 12 months. Other variables included age, body mass index, sex, performance status, and regular opioids and their doses. At the same time, they were asked to complete the Patient Assessment of Constipation Symptoms (PAC-SYM) and Patient Assessment of Constipation Quality of Life (PAC-QOL) questionnaires. Results: Descriptive statistics summarized baseline data. Unadjusted associations between the selected variables on PAC-SYM were examined by using bi-variate analyses. Significant variables identified on bi-variate analyses were included in a multivariate analysis. The final results identified that only the chronicity of constipation symptoms predicted more severe symptoms. This relationship persisted when this single variable was retained in the final model, illustrating that PAC-SYM scores are 0.41 higher in patients with chronic constipation compared with those without it (p = 0.02). In contrast, regular opioid use was not identified as a significant factor (p = 0.56). Discussion: This study suggests that the factor most likely to predict worse constipation symptoms was the duration that people had experienced problems. Further, those who perceived their constipation symptoms to be more severe had a poorer quality of life. More work is required to better define constipation risk factors and ways to best modify a patient's experiences

Can A Complex Online Intervention Improve Cancer Nurses’ Pain Screening and Assessment Practices? Results from a Multicenter, Pre-post Test Pilot Study

© 2017 American Society for Pain Management Nursing Unrelieved cancer pain has an adverse impact on quality of life. While routine screening and assessment forms the basis of effective cancer pain management, it is often poorly done, thus contributing to the burden of unrelieved cancer pain. The aim of this study was to test the impact of an online, complex, evidence-based educational intervention on cancer nurses' pain assessment capabilities and adherence to cancer pain screening and assessment guidelines. Specialist inpatient cancer nurses in five Australian acute care settings participated in an intervention combining an online spaced learning cancer pain assessment module with audit and feedback of pain assessment practices. Participants' self-perceived pain assessment competencies were measured at three time points. Prospective, consecutive chart audits were undertaken to appraise nurses' adherence with pain screening and assessment guidelines. The differences in documented pre-post pain assessment practices were benchmarked and fed back to all sites post intervention. Data were analyzed using inferential statistics. Participants who completed the intervention (n = 44) increased their pain assessment knowledge, assessment tool knowledge, and confidence undertaking a pain assessment (p < .001). The positive changes in nurses' pain assessment capabilities translated into a significant increasing linear trend in the proportion of documented pain assessments in patients’ charts at the three time points (χ2 trend = 18.28, df = 1, p < .001). There is evidence that learning content delivered using a spaced learning format, augmented with pain assessment audit and feedback data, improves inpatient cancer nurses' self-perceived pain screening and assessment capabilities and strengthens cancer pain guideline adherence

Inactivation of hypoxia inducible factor (HIF) 1 alpha induces obesity-associated metabolic disorders through brown adipose tissue dysfunction

published_or_final_versionThe 14th Medical Research Conference, Hong Kong, 10 January 2009. In Hong Kong Medical Journal, 2009, v. 15, suppl. 1, p. 40, article no. 6

Risks for heart disease and lung cancer from passive smoking by workers in the catering industry

Workers in the catering industry are at greater risk of exposure to secondhand smoke (SHS) when smoke-free workplace policies are not in force. We determined the exposure of catering workers to SHS in Hong Kong and their risk of death from heart disease and lung cancer. Nonsmoking catering workers were provided with screening at their workplaces and at a central clinic. Participants reported workplace, home, and leisure time exposure to SHS. Urinary cotinine was estimated by enzyme immunoassay. Catering facilities were classified into three types: nonsmoking, partially restricted smoking (with nonsmoking areas), and unrestricted smoking. Mean urinary cotinine levels ranged from 3.3 ng/ml in a control group of 16 university staff through 6.4 ng/ml (nonsmoking), 6.1 ng/ml (partially restricted), and 15.9 ng/ml (unrestricted smoking) in 104 workers who had no exposures outside of work. Workers in nonsmoking facilities had exposures to other smoking staff. We modeled workers' mortality risks using average cotinine levels, estimates of workplace respirable particulates, risk data for cancer and heart disease from cohort studies, and national (US) and regional (Hong Kong) mortality for heart disease and lung cancer. We estimated that deaths in the Hong Kong catering workforce of 200,000 occur at the rate of 150 per year for a 40-year working-lifetime exposure to SHS. When compared with the current outdoor air quality standards for particulates in Hong Kong, 30% of workers exceeded the 24-h and 98% exceeded the annual air quality objectives due to workplace SHS exposures. © 2006 Oxford University Press.postprin

Specific inhibition of cyclooxygenase-2 down-regulates NF-kappaB activation in gastric cancer cells by blocking its nuclear translocation

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Effectiveness of a Chinese herbal medicine preparation in the treatment of cough in uncomplicated upper respiratory tract infection: a randomised double-blinded placebo-control trial

BACKGROUND: Rigorous scientific and well-designed clinical trials to evaluate the effect of traditional Chinese medicine (TCM) is lacking. We, therefore, designed this study to evaluate the effectiveness of a commonly used TCM preparation in treating acute cough of uncomplicated URTI in adults and to search for a safe, effective and affordable alternative treatment for this common condition. METHODS: A randomised, double-blinded, placebo-control study comparing this TCM preparation with a placebo was conducted in 82 patients who attended the Family Medicine Training Centre, Prince of Wales Hospital, Hong Kong between November and December, 2003. The TCM herbal preparation includes nine commonly used TCM herbs for cough such as chuanbei, fangfeng, jiegeng, gancao and baibu (see Table 1) The treatment lasted for 5 days and patients were followed-up for another 6 days. Patients were asked to fill in a cough score and validated Leicester cough questionnaire (LCQ). RESULTS: 62 patients (75.6%) had completed the trial and no adverse effects were reported. Both intervened and control groups had improved in cough score and LCQ in the follow-up period, despite no overall statistical significance was observed in the differences of scores between the two groups. Women taking TCM had significantly fewer problems with sputum production (p = 0.03) and older subjects (>35 years of age) reported a significant improvement in hoarseness (p = 0.05) when compared to those using placebo. CONCLUSION: TCM was well-tolerated and received among the Hong Kong Chinese population. This TCM preparation appeared to have some benefits in the treatment of cough. Future research on TCM should concentrate more on commonly encountered conditions such as UTRI and cough. Our experience on the sensitivity of assessment tools used in detecting subtle differences in an otherwise self-limiting illness and clinical trial methodology when applying the underlying theory of how TCM works in disease management was invaluable